CN111478000A - Multi-zero-point band-pass balance filter adopting double-layer circular patches - Google Patents

Abstract

The invention discloses a multi-zero point band-pass balanced filter using a double-layer circular patch, including a multi-zero band-pass balanced filter using a double-layer circular patch, comprising an upper-layer dielectric substrate and a lower-layer dielectric substrate; The lower surface of the upper dielectric substrate is provided with a metal ground plate, and the upper surface of the upper dielectric substrate is provided with a first circular patch, a first input port feeder, a second input port feeder, a first slot line on the upper surface and a second slot line on the upper surface The metal ground plate is arranged on the upper surface of the lower dielectric substrate, and the lower surface of the lower dielectric substrate is provided with a second circular patch, a first output port feeder, a second output port feeder, a first slot line on the lower surface and a second slot on the lower surface. Wire. Compared with the prior art, the present invention designs a multi-zero band-pass balanced filter with double-layer circular patches by utilizing the resonance modes of the circular patches TM01, TM11 and TM21. In addition, the resonant frequency can also be changed by using the slot disturbance on the patch.

Description

A Multi-Zero Bandpass Balanced Filter Using Double-layer Circular Patches

technical field

The invention relates to the technical field of microwave passive devices, in particular to a multi-zero balanced filter using a double-layer circular patch.

Background technique

and V.C.Bengin,“Balanced Bandpass Filter Based on Square PatchResonators,”Telecomm.Mod.Sate.Cable Broad.Serv.,vol.,no.,pp.,Oct.2015.]、文献4[S.Y.Zheng,R.T.Wu and Z.W.Liu.“A Balanced Bandpass Filter with TwoTransmission Zeros Based on Square Patch Resonators,”IEEE Intern.Confer.onUbiquit.Wire.Broad.,vol.,no.,pp.,Oct.2016.]和文献5[Q.Liu,J.Wang and Y.He,“Compact Balanced Bandpass Filter Using Isosceles Right Triangular PatchResonator,”Electron.Lett.,vol.53,no.4,pp.253-254,Feb 2017.]Balanced circuits have a strong ability to resist environmental noise and electromagnetic interference, so the research in modern communication systems is due to literature 1 [Q.Liu, J.Wang, G.Zhang, L.Zhu and W.Wu, "A New Design Approach forBalanced Bandpass Filters on Right-Angled Isosceles Triangular PatchResonator,"IEEE Micro.Wireless Compon.Lett.,vol.29,no.1,pp.5-7,Dec.2018.] has attracted more and more attention. In recent years, patches have been developed for the design of high-performance microwave devices due to their low cost, small size, and ease of integration with planar microwave circuits. Therefore, a balanced passband filter composed of patch resonators was published in Document 2 [AMAbbosh, "Ultrawideband Balanced Bandpass Filter," IEEE Micro. Wireless Compon. Lett., vol. 21, no. 9, pp. 480-482 , Sept.2011.], Literature 3 [N.

and VCBengin, “Balanced Bandpass Filter Based on Square PatchResonators,” Telecomm.Mod.Sate.Cable Broad.Serv.,vol.,no.,pp.,Oct.2015.], Literature 4 [SYZheng,RTWu and ZWLiu.” A Balanced Bandpass Filter with TwoTransmission Zeros Based on Square Patch Resonators,"IEEE Intern.Confer.onUbiquit.Wire.Broad.,vol.,no.,pp.,Oct.2016.] and reference 5[Q.Liu,J. Wang and Y. He, "Compact Balanced Bandpass Filter Using Isosceles Right Triangular PatchResonator," Electron. Lett., vol. 53, no. 4, pp. 253-254, Feb 2017.]

In document 2 [A.M.Abbosh, "Ultrawideband Balanced Bandpass Filter," IEEEMicro.Wireless Compon.Lett., vol.21, no.9, pp.480-482, Sept.2011.] a wide-coupling structure is used to design a Balanced bandpass filter for broadband performance. The device adopts a three-layer lateral coupling structure. The top and bottom layers of the structure contain tapered patch resonators. Although the bandwidth of this design is wide, the return loss is greater than 10db due to the use of a wide coupling structure, and the structure is complex.

and V.C.Bengin,“Balanced Bandpass Filter Based onSquare Patch Resonators,”Telecomm.Mod.Sate.Cable Broad.Serv.,vol.,no.,pp.,Oct.2015.]和文献4[S.Y.Zheng,R.T.Wu and Z.W.Liu.“A Balanced Bandpass Filterwith Two Transmission Zeros Based on Square Patch Resonators,”IEEEIntern.Confer.on Ubiquit.Wire.Broad.,vol.,no.,pp.,Oct.2016.]中提出了一种由矩形槽的方形贴片谐振器构成的平衡带通滤波器。将两个端口位置合适的方形贴片谐振器级联在同一平面上，实现双模差分带通滤波器，但电路尺寸过大。In the literature 3 [N.

and VCBengin, "Balanced Bandpass Filter Based on Square Patch Resonators," Telecomm.Mod.Sate.Cable Broad.Serv.,vol.,no.,pp.,Oct.2015.] and Literature 4[SYZheng,RTWu and ZWLiu." A Balanced Bandpass Filterwith Two Transmission Zeros Based on Square Patch Resonators,"IEEEIntern.Confer.on Ubiquit.Wire.Broad.,vol.,no.,pp.,Oct.2016.] proposed a square A balanced bandpass filter composed of patch resonators. Two square patch resonators with suitable port positions are cascaded on the same plane to realize a dual-mode differential bandpass filter, but the circuit size is too large.

In reference 5 [Q.Liu, J.Wang and Y.He, "Compact Balanced Bandpass Filter Using Isosceles Right Triangular Patch Resonator," Electron.Lett., vol.53, no.4, pp.253-254, Feb 2017. ] and Reference 6 [Q.Liu, J.Wang, L.Zhu, G.Zhang, F.Huang and W.Wu, “ANew Balanced Bandpass Filter With Improved Performance on Right-AngledIsosceles Triangular Patch Resonator,” IEEE Micro.Theory A compact balanced bandpass filter based on an isosceles triangular patch resonator is proposed in Techni., vol.66, no.11, pp.4803-4813, Nov.2018.]. Using the placement of four triangular blocks to form a square reduces the size of the circuit, but doubles the size of the circuit.

Literature 6 [Q.Liu, J.Wang, L.Zhu, G.Zhang, F.Huang and W.Wu, "A New BalancedBandpass Filter With Improved Performance on Right-Angled IsoscelesTriangular Patch Resonator," IEEE Micro.Theory Techni. , vol.66, no.11, pp.4803-4813, Nov.2018.] constructed an improved triangular patch, one electric wall, two magnetic walls, literature 5 [Q.Liu, J.Wang and Y. He, "Compact Balanced Bandpass Filter Using Isosceles RightTriangular Patch Resonator," Electron. Lett., vol. 53, no. 4, pp. 253-254, Feb 2017.] has no oversizing issues. In the above article, square patches or patches that form square triangles are used, but circular patches are not studied.

The TM11 mode of the patch resonator is used in all the literature, and no other models are studied. This mode can only be used for lower frequencies. If the frequency is increased to a certain extent, the model will be reduced to a size that cannot be processed. .

SUMMARY OF THE INVENTION

The present invention provides a multi-zero band-pass balanced filter using a double-layer circular patch to solve the TM11 mode in which patch resonators are used in the prior art. At lower frequencies, if the frequency is increased to a certain extent, the model will be reduced to an unmanufacturable size.

Embodiments of the present invention provide a multi-zero bandpass balanced filter using a double-layer circular patch, including an upper-layer dielectric substrate and a lower-layer dielectric substrate;

The lower surface of the upper dielectric substrate is provided with a metal ground plate, and the upper surface of the upper dielectric substrate is provided with a first circular patch, a first input port feeder, a second input port feeder, a first slot line on the upper surface and an upper surface the second slot line;

The metal ground plate is arranged on the upper surface of the lower dielectric substrate, and the lower surface of the lower dielectric substrate is provided with a second circular patch, a first output port feeder, a second output port feeder, a first slot line on the lower surface and a lower surface Second slot line.

Further, in an implementation manner, the upper-layer dielectric substrate is a cuboid whose upper and lower surfaces are the same square, the lower-layer dielectric substrate and the upper-layer dielectric substrate have the same shape, and the lower-layer dielectric substrate and the upper-layer dielectric substrate are about a metal ground plate. Symmetrical up and down;

The center of the first circular patch is consistent with the center point of the upper dielectric substrate, the center of the second circular patch is consistent with the center point of the lower dielectric substrate, and the center of the first circular patch is consistent with the center point of the second circular patch. The straight line where the center of the circular patch is located is perpendicular to the plane where the upper surface of the upper dielectric substrate is located and the plane where the upper surface of the lower dielectric substrate is located.

Further, in an implementation manner, the first input port feed line includes a first input microstrip conduction band, one end of the first input microstrip conduction band extends to the first side of the upper dielectric substrate, and the other end extends To the side of the first circular patch, the straight line where the two ends of the conduction band of the first input microstrip are located is perpendicular to the straight line where the first side is located, and the center of the first circular patch is on the first input microstrip. The two ends of the belt guide are on the straight line;

The second input port feed line includes a second input microstrip wire, one end of the second input microstrip wire extends to the second side of the upper dielectric substrate, and the other end extends to the side of the first circular patch , the line where the two ends of the feeder of the second input port are located is perpendicular to the line where the second side is located, and the center of the first circular patch is on the line where the two ends of the feeder of the second input port are located; the first side and The second sides are perpendicular to each other.

Further, in an implementation manner, the straight line where the two ends of the feeder of the first input port are located is perpendicular to the line where the two ends of the feeder of the second input port are located, and the line where the two ends of the feeder of the first input port are located is perpendicular to the line where the two ends of the feeder of the second input port are located. The lines at the two ends intersect at the center of the first circular patch.

Further, in an implementation manner, the first output port feed line includes a first output microstrip conduction band, one end of the first output microstrip conduction band extends to the third side of the lower dielectric substrate, and the other end extends To the side of the second circular patch, the line where the two ends of the first output microstrip conduction band are located is perpendicular to the line where the third side is located, and the center of the second circular patch is on the first output microstrip. The two ends of the belt guide are on the straight line;

The second output port feed line includes a second output microstrip wire, one end of the second output microstrip wire extends to the fourth side of the lower dielectric substrate, and the other end extends to the side of the second circular patch , the straight line where the two ends of the second output microstrip wire are located is perpendicular to the fourth side, and the center of the second circular patch is on the straight line where the two ends of the second output microstrip wire are located;

The third side and the fourth side are perpendicular to each other.

Further, in an implementation manner, the straight line where the two ends of the first output microstrip conduction band are located is perpendicular to the straight line where the two ends of the second output microstrip conductor are located, and the straight line where the two ends of the first output microstrip conduction band are located is the same as The two ends of the second output microstrip wire intersect with the center of the second circular patch.

Further, in an implementation manner, the line where the two ends of the feeder line of the first input port are located is perpendicular to the line where the two ends of the feeder line of the second input port are located, and intersect at the midpoint of the upper dielectric substrate, and the first groove line on the upper surface is perpendicular to the line. and the second slot line on the upper surface is located on the diagonal line A1A2 of the upper dielectric substrate, and the first input port feed line and the second input port feed line are respectively located on both sides of the diagonal line A1A2.

Further, in an implementation manner, the straight line where the two ends of the feeder line of the first output port are located is perpendicular to the line where the two ends of the feeder line of the second output port are located, and intersects at the midpoint of the lower dielectric substrate, and the first groove line on the lower surface is perpendicular to the line. and the second groove line on the lower surface are located on the diagonal line B1B2 of the lower dielectric substrate, and the feed line of the first output port and the feed line of the second output port are respectively located on both sides of the diagonal line B1B2.

Further, in an implementation manner, the metal ground plate is provided with a first ground slot line, a second ground slot line, a third ground slot line and a fourth ground slot line;

The first ground slot line is located on the center line D1D2 of the metal ground plate, the third ground slot line is located on the center line C1C2 of the metal ground plate, and the first ground slot line and the third ground slot line are relative to the center of the metal ground plate. Line D1D2 is axisymmetric;

The second ground slot line is located on the center line D1D2 of the metal ground plate, and the fourth ground slot line is located on the center line C1C2 of the metal ground plate. The second ground slot line and the fourth ground slot line are about the center line of the metal ground plate C1C2 Axisymmetric;

The extension lines of the first ground slot line and the third ground slot line are perpendicular to the extension lines of the second ground slot line and the fourth ground slot line, and intersect at the center point of the metal grounding plate.

In the prior art, the TM11 mode of the patch resonator is used, and other models have not been studied, and this mode can only be used for lower frequencies. If the frequency increases to a certain extent, the model will be reduced to the point where it cannot be processed. size. However, the present invention utilizes the TM21 mode of the circular patch resonator to design a balanced passband filter, so that higher frequencies in the wireless communication system can be utilized. Compared with the square, the circle has a smaller area (πr ² <4r ² ) under the same radius, and the degenerate modulus of the circle is more flexible. Due to the specific boundary conditions of the circular patch, the proposed resonator can suppress the TM01 and TM11 modes while maintaining the TM21 mode. In this case, a second-order balanced bandpass filter with three transmission zeros is constructed by appropriately establishing the coupling scheme of the two-layer patch. Therefore, compared with the prior art, a multi-zero band-pass balanced filter with double-layer circular patches is designed by using the resonant modes of the circular patches TM01, TM11 and TM21. In addition, the resonant frequency can also be changed by using the slot disturbance on the patch.

Description of drawings

In order to illustrate the technical solutions of the present invention more clearly, the accompanying drawings required in the embodiments will be briefly introduced below. Obviously, for those of ordinary skill in the art, without creative work, the Additional drawings can be obtained from these drawings.

1 is a schematic three-dimensional structure diagram of a multi-zero bandpass balanced filter using a double-layer circular patch provided in an embodiment of the present invention;

2 is a schematic plan view of a multi-zero point bandpass balanced filter using a double-layer circular patch provided in an embodiment of the present invention;

3 is a schematic diagram of plane dimensioning of a multi-zero band-pass balanced filter using a double-layer circular patch provided in an embodiment of the present invention;

4 is a waveform diagram of a multi-zero bandpass balanced filter using a double-layer circular patch provided in an embodiment of the present invention;

5 is a phase diagram of a multi-zero bandpass balanced filter using a double-layer circular patch provided in an embodiment of the present invention;

Among them, 11-upper dielectric substrate, 12-lower dielectric substrate, 2-metal ground plate, 31-first circular patch, 32-second circular patch, 4-first input port feeder, 5-second Input port feeder, 61- the first slot line on the upper surface, 62- the second slot line on the upper surface, 63- the first slot line on the lower surface, 64- the second slot line on the lower surface, 7- the first output port feed line, 8- The feeder line of the second output port, 91-the first ground slot line, 92-the second ground slot line, 93-the third ground slot line, and 94-the fourth ground slot line.

Detailed ways

In order to make the above objects, features and advantages of the present invention more clearly understood, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

The embodiment of the present invention discloses a multi-zero band-pass balanced filter using a double-layer circular patch, which is applied to the front-end filtering part of a wireless communication system or a radar system. Anti-environmental noise and electromagnetic interference function.

As shown in FIG. 1 and FIG. 2 , this embodiment discloses a multi-zero bandpass balanced filter using a double-layer circular patch, including an upper-layer dielectric substrate 11 and a lower-layer dielectric substrate 12 ;

The lower surface of the upper dielectric substrate 11 is provided with a metal ground plate 2, and the upper surface of the upper dielectric substrate 11 is provided with a first circular patch 31, a first input port feeder 4, a second input port feeder 5, a groove line 61 and a second groove line 62 on the upper surface;

The metal ground plate 2 is arranged on the upper surface of the lower dielectric substrate 12, and the lower surface of the lower dielectric substrate 12 is provided with a second circular patch 32, a first output port feeder 7, a second output port feeder 8, A slot line 63 and a second slot line 64 on the lower surface.

In the multi-zero bandpass balanced filter using double-layer circular patches described in this embodiment, the upper-layer dielectric substrate 11 is a rectangular parallelepiped whose upper and lower surfaces are the same square, and the lower-layer dielectric substrate 12 and the upper-layer dielectric substrate 11 has the same shape, and the lower dielectric substrate 12 and the upper dielectric substrate 11 are symmetrical about the metal ground plate 2 up and down;

The center of the first circular patch 31 is consistent with the center point of the upper dielectric substrate 11 , the center of the second circular patch 32 is consistent with the center point of the lower dielectric substrate 12 , the first circular patch 31 The line between the center of the circle and the center of the second circular patch 32 is perpendicular to the plane where the upper surface of the upper dielectric substrate 11 is located and the plane where the upper surface of the lower dielectric substrate 12 is located.

In the multi-zero band-pass balanced filter using a double-layer circular patch described in this embodiment, the first input port feeder 4 includes a first input microstrip conduction band 41, and the first input microstrip One end of the conduction strip 41 extends to the first side edge 1101 of the upper dielectric substrate 11 , and the other end extends to the side edge of the first circular patch 31 . The line between the two ends of the first input microstrip conduction strip 41 is perpendicular to the The line where the first side edge 1101 is located, the center of the first circular patch 31 is located on the line where both ends of the first input microstrip conduction band 41 are located;

The second input port feeder 5 includes a second input microstrip wire 51, one end of the second input microstrip wire 51 extends to the second side 1102 of the upper dielectric substrate 11, and the other end extends to the first circular On the side of the patch 31 , the line where the two ends of the second input port feeder 5 are located is perpendicular to the line where the second side 1102 is located, and the center of the first circular patch 31 is where the two ends of the second input port feeder 5 are located. On a straight line; the first side 1101 and the second side 1102 are perpendicular to each other.

In the multi-zero bandpass balanced filter using the double-layer circular patch described in this embodiment, the straight line where the two ends of the feeder line 4 of the first input port are located is perpendicular to the line where the two ends of the feeder line 5 of the second input port are located. The line where the two ends of the first input port feeder 4 are located and the line where the two ends of the second input port feeder 5 are located intersect at the center of the first circular patch 31 .

In the multi-zero band-pass balanced filter using a double-layer circular patch described in this embodiment, the first output port feeder 7 includes a first output microstrip conduction band 71, and the first output microstrip One end of the conduction strip 71 extends to the third side edge 1201 of the lower dielectric substrate 12 , and the other end extends to the side edge of the second circular patch 32 . The line between the two ends of the first output microstrip conduction strip 71 is perpendicular to the The line where the third side edge 1201 is located, the center of the second circular patch 32 is located on the line where the two ends of the first output microstrip conduction band 71 are located;

The second output port feed line 8 includes a second output microstrip wire 81 , one end of the second output microstrip wire 81 extends to the fourth side 1202 of the underlying dielectric substrate 12 , and the other end extends to the second circular On the side of the patch 32 , the line at the two ends of the second output microstrip wire 81 is perpendicular to the fourth side 1202 , and the center of the second circular patch 32 is at the two ends of the second output microstrip wire 81 . On a straight line; the third side 1201 and the fourth side 1202 are perpendicular to each other.

In the multi-zero band-pass balanced filter using the double-layer circular patch described in this embodiment, the straight line where the two ends of the first output microstrip conducting strip 71 are located and the two ends of the second output microstrip conducting strip 81 are located The straight line is vertical, and the straight line where the two ends of the first output microstrip conducting strip 71 and the two ends of the second output microstrip conductor 81 are intersected at the center of the second circular patch 32 .

In the multi-zero bandpass balanced filter using the double-layer circular patch described in this embodiment, the straight line where the two ends of the feeder line 4 of the first input port are located is perpendicular to the line where the two ends of the feeder line 5 of the second input port are located. Intersecting at the midpoint of the upper dielectric substrate 11, the upper surface first slot line 61 and the upper surface second slot line 62 are located on the diagonal A1A2 of the upper dielectric substrate 11, the first input port feed line 4 and the second input The port feeders 5 are located on both sides of the corner line A1A2, respectively.

In the multi-zero band-pass balanced filter using the double-layer circular patch described in this embodiment, the straight line where the two ends of the feeder line 7 of the first output port are located is perpendicular to the line where the two ends of the feeder line 8 of the second output port are located. Intersecting at the midpoint of the lower dielectric substrate 12, the lower surface first slot line 63 and the lower surface second slot line 64 are located on the diagonal B1B2 of the lower dielectric substrate 12, the first output port feed line 7 and the second output The port feeders 8 are located on both sides of the diagonal line B1B2, respectively.

In the multi-zero band-pass balanced filter using double-layer circular patches described in this embodiment, the metal ground plate 2 is provided with a first ground slot line 91, a second ground slot line 92, a third ground slot line 92, and a third ground slot line 92. Ground slot line 93 and fourth ground slot line 94;

The first ground slot line 91 is located on the center line D1D2 of the metal ground plate 2, the third ground slot line 93 is located on the center line C1C2 of the metal ground plate 2, the first ground slot line 91 and the third ground slot line 93 Axisymmetric about the center line D1D2 of the metal ground plate 2;

The second ground slot line 92 is located on the center line D1D2 of the metal grounding plate 2, and the fourth ground slot line 94 is located on the center line C1C2 of the metal grounding plate 2. The second ground slot line 92 is related to the fourth ground slot line 94. The center line C1C2 of the metal ground plate 2 is axisymmetric;

The extension lines of the first ground slot line 91 and the third ground slot line 93 are perpendicular to the extension lines of the second ground slot line 92 and the fourth ground slot line 94 , and intersect at the center point of the metal ground plate 2 .

In the multi-zero band-pass balanced filter using double-layer circular patches described in this embodiment, the first slot line 61 on the upper surface and the second slot line 62 on the upper surface affect the resonance mode TM21 to form a passband. TM01, TM11 (a pair of degenerate modes) and TM21 (another degenerate mode) form 4 transmission zeros.

The multi-zero-point bandpass balanced filter using double-layer circular patches described in this embodiment is manufactured by processing and corroding the metal surfaces on the front and back of the circuit substrate through the printed circuit board manufacturing process, so as to form the required The metal pattern is simple in structure and can be realized on a single PCB board, which is convenient for processing and integration. At the same time, the design not only realizes the function of balance, but also realizes the function of multi-zero point filtering, and because of the use of circular patches, the circuit space is fully utilized, and the circuit volume is greatly reduced. Using the slot line to affect the resonant mode TM21 of the patch, a multi-zero balanced bandpass filter with good common mode rejection is designed. The present invention will be described in further detail below.

The structure of a multi-zero point bandpass balanced filter using a double-layer circular patch described in this embodiment is shown in FIG. 1 , the top view is shown in FIG. 2 , and the relevant size specifications are shown in FIG. 3 . The substrates used for the upper dielectric substrate 11 and the lower dielectric substrate 12 are RO4003C substrates, the relative permittivity is 3.55, the thickness is 0.508 mm, and the loss tangent is 0.0027. Combined with Figure 4, the size parameters of the multi-zero bandpass balanced filter using the double-layer circular patch are as follows: r=8.0mm, l1=13mm, W1=0.4mm, the multi-zero bandpass of the double-layer circular patch The total area of the balanced filter excluding the input and output microstrip guide bands is 16×16mm2, and the corresponding guide wavelength size is 0.65λg×0.65λg, where λg is the length of the waveguide at the center frequency.

In this example, the multi-zero band-pass balanced filter using the double-layer circular patch is modeled and simulated in the electromagnetic simulation software HFSS.13.0. Figure 4 is the S parameter of the multi-zero bandpass balanced filter using the double-layer circular patch in this example. It can be seen from the figure that the center frequency of the multi-zero bandpass balanced filter using the double-layer circular patch are 6.5GHz and 0.52GHz with 3-dB bandwidth, less than 30dB return loss in passband, 0.5dB minimum insertion loss, and 40dB common mode rejection. Figure 5 shows the phase parameters of the multi-zero band-pass balanced filter using the double-layer circular patch in this example. It can be seen that the phase difference in the passband is about 180 degrees.

To sum up, a multi-zero point bandpass balanced filter using a double-layer circular patch in this embodiment is described. Using the resonant modes of the circular patches TM01, TM11 and TM21, a multi-zero band-pass balanced filter with double-layer circular patches is designed. Additionally, slot perturbations on the patch are used to change the resonant frequency. This multi-zero bandpass balanced filter is very suitable for modern wireless communication systems.

The present invention provides an idea and method for a multi-zero bandpass balanced filter using a double-layer circular patch. There are many specific methods and approaches for realizing this technical solution. The above are only the preferred embodiments of the present invention, and should It is pointed out that for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can also be made, and these improvements and modifications should also be regarded as the protection scope of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims (9)

1. A multi-zero bandpass balanced filter employing a double-layer circular patch, characterized in that it comprises an upper-layer dielectric substrate (11) and a lower-layer dielectric substrate (12); A metal ground plate (2) is provided on the lower surface of the upper dielectric substrate (11), and a first circular patch (31), a first input port feeder (4), a first circular patch (31), a first input port feeder (4), The second input port feed line (5), the first slot line (61) on the upper surface and the second slot line (62) on the upper surface; The metal ground plate (2) is arranged on the upper surface of the lower dielectric substrate (12), and the lower surface of the lower dielectric substrate (12) is provided with a second circular patch (32), a first output port feeder (7), The second output port feed line (8), the first slot line (63) on the lower surface and the second slot line (64) on the lower surface. 2. A kind of multi-zero bandpass balanced filter using double-layer circular patch according to claim 1, characterized in that, the upper dielectric substrate (11) is a rectangular parallelepiped whose upper and lower surfaces are the same square, and the The lower-layer dielectric substrate (12) and the upper-layer dielectric substrate (11) have the same shape, and the lower-layer dielectric substrate (12) and the upper-layer dielectric substrate (11) are vertically symmetrical with respect to the metal ground plate (2); The center of the first circular patch (31) is consistent with the center point of the upper dielectric substrate (11), and the center of the second circular patch (32) is consistent with the center point of the lower dielectric substrate (12). The line between the center of the first circular patch (31) and the center of the second circular patch (32) is perpendicular to the plane where the upper surface of the upper dielectric substrate (11) is located and the plane where the upper surface of the lower dielectric substrate (12) is located. 3. a kind of multi-zero band-pass balanced filter using double-layer circular patch according to claim 2, is characterized in that, described first input port feeder (4) comprises the first input microstrip conduction band ( 41), one end of the first input microstrip conduction band (41) extends to the first side edge (1101) of the upper dielectric substrate (11), and the other end extends to the side of the first circular patch (31) side, the straight line where the two ends of the first input microstrip conduction band (41) are located is perpendicular to the straight line where the first side edge (1101) is located, and the center of the first circular patch (31) is in the first input microstrip conduction band. The two ends of the belt (41) are on a straight line; The second input port feeder (5) includes a second input microstrip wire (51), and one end of the second input microstrip wire (51) extends to the second side (1102) of the upper dielectric substrate (11), The other end extends to the side of the first circular patch (31), the line where the two ends of the second input port feeder (5) are located is perpendicular to the line where the second side (1102) is located, and the first circle The center of the shape patch (31) is on the straight line where the two ends of the feeder line (5) of the second input port are located; The first side edge (1101) and the second side edge (1102) are perpendicular to each other. 4. a kind of multi-zero band-pass balanced filter adopting double-layer circular patch according to claim 3, it is characterized in that, described first input port feeder (4) both ends of the straight line and the second input port The straight line where the two ends of the feeder line (5) are located is perpendicular, and the line where the two ends of the feeder line (4) at the first input port are located intersects with the center of the first circular patch (31) with the line where the two ends of the feeder line (5) at the second input port are located . 5. a kind of multi-zero bandpass balanced filter using double-layer circular patch according to claim 1, is characterized in that, described first output port feeder (7) comprises the first output microstrip conduction band ( 71), one end of the first output microstrip conduction band (71) extends to the third side edge (1201) of the lower dielectric substrate (12), and the other end extends to the side of the second circular patch (32) side, the straight line where the two ends of the first output microstrip conduction band (71) are located is perpendicular to the straight line where the third side edge (1201) is located, and the center of the second circular patch (32) is at the first output microstrip conduction band. The two ends of the belt (71) are on a straight line; The second output port feeder (8) includes a second output microstrip wire (81), and one end of the second output microstrip wire (81) extends to the fourth side (1202) of the lower dielectric substrate (12), The other end extends to the side of the second circular patch (32), and the line between the two ends of the second output microstrip wire (81) is perpendicular to the fourth side (1202). The center of the patch (32) is on a straight line where both ends of the second output microstrip wire (81) are located; The third side (1201) and the fourth side (1202) are perpendicular to each other. 6. a kind of multi-zero band-pass balanced filter using double-layer circular patch according to claim 5, is characterized in that, described first output microstrip conduction band (71) both ends of the straight line and the second The straight line where the two ends of the output microstrip conductor (81) are located is vertical, and the straight line where the two ends of the first output microstrip conductor (71) are located intersects with the straight line where the two ends of the second output microstrip conductor (81) are located on the second circular sticker. The center of the slice (32). 7. a kind of multi-zero bandpass balanced filter using double-layer circular patch according to claim 5, is characterized in that, described first input port feeder (4) both ends of the straight line and the second input port The two ends of the feeder line (5) are perpendicular to the straight lines and intersect at the midpoint of the upper dielectric substrate (11), and the first groove line (61) on the upper surface and the second groove line (62) on the upper surface are located on the upper dielectric substrate (11) On the diagonal line A1A2, the first input port feeder line (4) and the second input port feeder line (5) are respectively located on both sides of the diagonal line A1A2. 8. a kind of multi-zero point bandpass balanced filter using double-layer circular patch according to claim 6, is characterized in that, described first output port feeder (7) both ends of the straight line and the second output port The straight lines where the two ends of the feeder line (8) are located are perpendicular and intersect at the midpoint of the lower dielectric substrate (12). On the diagonal line B1B2, the first output port feeder line (7) and the second output port feeder line (8) are respectively located on both sides of the diagonal line B1B2. 9. The multi-zero band-pass balanced filter using a double-layer circular patch according to claim 7, wherein the metal ground plate (2) is provided with a first ground slot line (91) , the second ground slot line (92), the third ground slot line (93) and the fourth ground slot line (94); The first ground slot line (91) is located on the center line D1D2 of the metal ground plate (2), the third ground slot line (93) is located on the center line C1C2 of the metal ground plate (2), and the first ground slot line The line (91) and the third ground slot line (93) are axisymmetric about the center line D1D2 of the metal ground plate (2); The second ground slot line (92) is located on the center line D1D2 of the metal ground plate (2), the fourth ground slot line (94) is located on the center line C1C2 of the metal ground plate (2), and the second ground slot line ( 92) Axisymmetric with the fourth ground slot line (94) about the center line C1C2 of the metal ground plate (2); The extension lines of the first ground slot line (91) and the third ground slot line (93) are perpendicular to the extension lines of the second ground slot line (92) and the fourth ground slot line (94), and intersect at the the center point of the metal ground plate (2).

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